What do I do now? Iron Man is helpless against an enemy with the ability to melt iron! And yet, without my other identity, I'm just an ordinary human... More vulnerable than most because my heart would stop without my chest plate! (...) What's the matter with me? I'm still not helpless! I've still got the greatest weapon in the world... a human brain!

Bruno Horgan, one of Anthony Stark’s former competitors, is on a rampage as the Melter. The Melter has been sabotaging Stark's weapons, embarrassing him in front of his military customers during an unveiling ceremony. While checking his inventory, Stark is ambushed and knocked unconscious by the Melter. As he stands over Stark’s unconscious body, he reflects on how he became the Melter. Bruno Horgan was once a competitor of Stark Industries who was bankrupted when Stark turned in a report to the Pentagon showing that Horgan was doing substandard work on his defense projects. While overseeing the disassembly of his factory, Horgan discovered malfunctioning inspection device that produced a beam capable of melting iron. He reconfigured this device into a melting beam weapon and created the identity of the Melter in order to get revenge against his enemies, including Anthony Stark. The Melter leaves the unconscious Stark behind and continues with his business of sabotage.

Happy Hogan finds the unconscious Stark and takes him back to his office. Once in private, Stark plugs in his chest plate and convalesces. Meanwhile, the Melter is running loose in Stark's manufacturing facility. As the Melter is focusing on a large generator, Iron Man appears on the scene. The Melter turns his melting beam on Iron Man's armor and completely melts off the armor’s left arm! Fearing damage to his chest plate, Iron Man hastily retreats, using his armor’s magnets to break open a steam pipe to drive the villain away.

Later, Stark focuses his attention on repairing the damage caused by the Melter. He is called to Washington DC, where he has to explain to members of the Defense Appropriation committee that he has been unable to deliver a reliable product due to the acts of sabotage perpetrated by the Melter. Several of the senators even doubt the existence of the Melter.

Back at Stark Industries, Iron Man assists the repair crews by clearing away the wreckage left by the Melter. He has resolved to take the fight to the villain so he can get his life back. While he is working, the Melter spots him and decides to wage his final assault against Iron Man! He walks up to Iron Man and completely melts the large chunk of scrap metal he is holding over his head, covering him with molten metal, which Iron Man clears away using his jet blowers. The Melter turns his beam onto Iron Man once again, this time with no effect! The astonished Melter then melts through a crane that is holding a large boulder above a crowd of bystanders that includes Happy Hogan and Pepper Potts. Iron Man saves the crowd from the falling boulder, then pursues the fleeing Melter. After a brief showdown, the Melter melts a hole through the floor and escapes into the currents of an underground sewer system.

Iron Man reveals that he tricked the Melter. He had redesigned the armor he is wearing, making it from tough extruded aluminum so that it was immune to the Melter’s Melting Ray.